Current Measurement And Plasma Diagnostic Of Electron Beam Plasma

The main work of this thesis covered two parts, respectively, electron beam current measurement and electron beam plasma(EBP) diagnostic. On our electron-beam-plasma platform, electrons were generated by the thermal cathode, accelerated by high voltage and carried out through continual vacuum system. Accurate current measurement was necessary for not only the electron beam plasma research, but also for the study of electron beam transmission efficiency through the continual vacuum system. And Langmuir probe and optical spectrum instrument were used for the electron beam plasma diagnostic.During the experiments, Rogowski Coil and Faraday Cage were designed for this electron beam plasma system, by which, the current was measured. And method for processing the Rogowski Coil signal, operating between self-integral type and differential type, was provided in this paper. The electron beam current wave was obtained by the designed Rogowski Coil, as well as,Faraday Cage. Results showed that two methods for current measurement was identical. Meanwhile, emission current of the system, was calibrated by the measurement results and current transmission efficiency was obtained, which showed that transmission efficiency declined under high operating pressure. Further more, instability of emission electron beam was discovered by the results, which was caused by the space charge effect in electron generation area.As for Ar EBP diagnostic, Langmuir probe system was established in our experiment. Results showed that the existing of high energy electron beam had effects on the Ⅴ-Ⅰ curve, which was obvious near the middle of electron beam. By analyzing the probe data, radial distribution of Electron density, temperature as well as, plasma potential, were obtained, under different pressure and current. At the same time, simple optical diagnostic was used for plasma. Camera recorded the pictures of Ar EBP under different pressure and current, and picture processing showed the same results as Monte-Carlo simulation. Spectrum instrument recorded the line spectrum of Ar, and line spectrum was mostly between680nm and900nm, while the continuous spectrum was very weak.